Exhaust sleeves are used in growing crystals using the Czocharalski technique for removing exhaust process gases from a growing furnace. Exhaust sleeves are often made of graphite because of its useful high temperature properties. During the crystal growing process, however, silicon oxides and silicon carbides are often built-up on the surface of the exhaust sleeve. This buildup negatively impacts the evacuation process, and in a severe situation, it can lead to contamination through nitrogen flow in undesirable areas. Accordingly, the buildup in an exhaust sleeve requires that the exhaust sleeve be frequently replaced and/or cleaned.
Therefore, it is desirable to provide an apparatus and a method which can substantially reduce the buildup of silicon oxides and silicon carbides on the surface of exhaust sleeves, thus allowing more uniform laminar flow of process gases in the Cz chamber and exhaust sleeve and extending the lifetime of exhaust sleeves as well.